Add an ability to display [almost] independent groups of icons.

• Basic core changes
• GUI changes
• New IG must copy options from the current IG
• Review Interrupt tracker and Additions data sources
• DB migration
• DB profile handling
• Add handler for smth like "group:1" to spell's search box
• Move the Spells tab
• Don't forget to publish LRD
• Use new C_UnitAura API
• Publish the beta version
• Publish release version